1. Field of the Invention
The present invention relates to a indicating system for automotive lamps for informing a driver of the inoperativeness of one or more lamps.
2. Description of the Prior Art
In a conventional indicating system of this kind, for example as exemplified in the U.S. Pat. No. 3,868,628, which granted on Feb. 25, 1975 to Yasuhiko Sakurai, a current winding is connected between a current source and a plurality of automotive lamps and a voltage winding is connected between the current source and ground for generating an opposite magnetomotive force to that of the current winding. A lamp interruption is detected in such a manner that a relay is energized to light an indicating lamp when the net magnetomotive force of the two windings exceeds a predetermined value.
However, the conventional system just described sometimes fails to indicate lamp interruption when all of the lamps are inoperative, since the magnetomotive force of the voltage winding in itself is still large enough to maintain the relay at its normal condition.